Conceptually I understand that "Ubuntu" itself is basically the kernel and package management stuff, the operating system.
I am still a little confused about the difference between "Gnome" and "Gnome Shell" and also "KDE" and "KDE Plasma".
Kubuntu is defined as: "an official flavour of the Ubuntu operating system which uses the KDE Plasma Desktop"
So, what is the difference between installing Kubuntu and installing Ubuntu (with Gnome) and then installing the "KDE Plasma" desktop instead of Gnome shell?
Does KDE Plasma somehow run better if it is not installed in Gnome?